Field of the Invention
This invention relates generally to the field of geophysical exploration for hydrocarbons. More specifically, the invention relates to methods of creating and interpreting mosaics of multiple seismic surveys.
Background of the Invention
A seismic survey is a method of imaging the subsurface of the earth by delivering acoustic energy down into the subsurface and recording the signals reflected from the different rock layers below. The source of the acoustic energy typically comes from a seismic source such as without limitation, explosions or seismic vibrators on land, and air guns in marine environments. During a seismic survey, the seismic source may be moved across the surface of the earth above the geologic structure of interest. Each time a source is detonated or activated, it generates a seismic signal that travels downward through the earth, is reflected, and, upon its return, is recorded at different locations on the surface by receivers. The recordings or traces are then combined to create a profile of the subsurface that can extend for many miles. In a two-dimensional (2D) seismic survey, the receivers are generally laid out along a single straight line, whereas in a three-dimensional (3D) survey the receivers are distributed across the surface in a grid pattern. A 2D seismic line provides a cross sectional picture (vertical slice) of the earth layers as arranged directly beneath the recording locations. A 3D survey produces a data “cube” or volume that theoretically represents a 3D picture of the subsurface that lies beneath the survey area.
In the oil and gas industry, the primary goal of seismic exploration is locating subterranean features of interest within a seismic volume processed from data from a single seismic survey. However, on occasion, examining subterranean features of interest over a larger region encompassing multiple surveys is desirable. Current geophysical interpretation technology provides for limited manipulation and rendering of more than one seismic survey at a time. Present technology only provides the capabilities to couple z-slices from multiple volumes within a single seismic survey and to render a seismic volume in this fashion. Also, some systems can display multiple 3D surveys at a time in one window, but manipulation of the data is cube-by-cube and is therefore cumbersome and time consuming. One current solution that allows rendering of z-slices of multiple surveys is to first merge the data from these surveys into one single survey. Another solution is to take static pictures through amplitude extractions from individual seismic surveys at multiple levels and then build composite regional maps using these inputs. However, the first solution is time consuming and expensive while the second solution is static, and does not provide a dynamic display through all the adjacent seismic surveys
Consequently, there is a need for methods and systems of creating and interpreting mosaics of multiple seismic surveys.